Gear manufacture



C. E. DERR GEAR MANUFACTURE. APPLICATION FILED-OCT. 1|. 1912.

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APPLICATION FILED OCT. H, 1912.

Patented Feb. 10,1920.

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GEAR MANUFACTURE.

APPLICATION FILED OCT. 11, I912.

Patented Feb. 10, 1920.

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GEAR MANUFACTURE.

APPLICATION FILED OCT. 11, 19x2.

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Allarneyj WITNESSES UNITED STATES PATENT OFFICE.

CHAIR-LES E.

DEER, or DETROIT, MICHIGAN, Assxenon, siz'ivrnsnn ASSIGNMENTS, 'ro

JAMES E. GLEASON, TRUSTEE, or ROCHESTER, 'NEW YORK.

GEAR MANUFACTURE.

Specification of Letters Patent. Patented Feb, 10, 1920.

Application filed October 11, 1912. Serial No. 725,328.

To all whom it may concern Be it known that I, CHARLES vE. DEER, a citizen of the United States, and resident of Detroit, Wayne county, State of Michigan,

have inventedcertain new and useful Improvemcnts'in Gear Manufacture, ofwhich the following is a specification.

This invention relates to gear manufacr ture and more partlcularly to a method of cutting gears having curved teeth, and to machines for carrying out my method One form of machine for carrying out my method is shown in the accompanying drawings and hereinafter described, this machine embodying. improvements in the type of machine described in Patents N'os. 2913844, dated March 11, .1884, and 665,054, dated January 1, 1901. Both ofsaid. pat

, ents relate to machines for cutting gears of the bevel type, on what is called in the earlier of said patents the pri-nciple of evolution. These patents, however, are l1mited to the theory of, and machines for,

cutting bevel gears having straight teeth,

as distinguished from bevel gears having curved or irregularly shaped teeth.

In the drawings Figure l is a side elevation, partly in section of the improved machine;

Fig. 2 1s a plan vlew, partly in section with some of the parts removed, and with the gear blank and its arbor shown in dotted lines'.

3 is a section through the blankarbor bearing and spacing head on the line 3-3 of Fig. 4;

Fig. 4 1s a section through the spacing head on the line Hof Fig. 3;

Fig. 5 is a similar section showing the working parts in a different position-g.-

. Fig. 6 is a top view of the spacing head corresponding to the. sections shown in Figs. 4 and 5;

' Fig. '7 is an elevation of the spacing head.

shown in Fig. 1,taken from the other side of the head;

Fig. 8 is a vertical section through the v head and ,tool support, and showing the tool in raised position; Fig. 9 is a fragmentary plan view, showing the .cam plate in reverse position;

Figs. 10 and 11 are detail views of a modified form of tool and tool holder; and

Fig. 12 is an end view of an arbor'fiange; Fig. 13 is a plan of a segment of a crown shown in Fig. 13

-gear having teeth which are conjugate t0 the teeth of the gear shown in Fig. 1, the

teeth of the crown gear being sectioned on line 13'13 of Fig. 1 1; Fig. 1 1 is a section of the crown wheel wheel Fig. 15 1s a side view of partsshown in in the maand an i-ntermeshing bevel chine herein shown for carrying out this 7 method, the frame or bed of the machine is indicated at 20, and upon the left end of the frame, as'shownin Fig. 1, is mountedthe means for supporting and operating the gear blank. This supporting means consists principally of a plate 21 mounted upon a 1 flat upper surface 22 of the frame, and having' a series of circular grooves 23in which fit the corresponding circular flanges 24 of a securing plate 25, which is fastened to the frame by the screws 26. The circumference of the plate 21 is formed with gear teeth 27, with which meshes a worm 28 driven by a shaft 29, whereby the plate 21 is rotated or oscillated about a vertical axis which passes through the apex of the former-cone, hereinafter described.

The plate 21 carries two uprights 30 between which is-adjustably, held'a block or bearing 31, as by bolts 32; Thus this bearing is adjustable about the apex of the former-cone for operation upon different sized gears or blanks.

The blank 33 is removably clamped to the arbor 3% which operates in the bearing 31,

and upon the upper end of the arbor is rotatably mounted the housin '35 ofthe spac ing 'head, the lower part of t s housing com prising the former-cone 36, which isa prowhich hasone end attached to the cone and the other to the body of the machine in such a way that one band prevents the slipping of the cone in one direction and the other in the other direction, the said cone is so held that when the grooved plate 21- is .duction of-the pitch cone of the blank 33. By means of two .steel bands 37, each on oscillated, the cone will assume a motion as of a cone rolling on a plane without slip. If the housing 35, of which the said cone is a part, were coupled to the blank arbor 34, this rolling motion would be transmitted to the blank 33, thereby imparting to the latter that motion which is necessary to cause the tool togenerate the proper'tooth contour. i As a matter of fact, however, the housing 35 is only intermittently coupled to the. arbor 34namely, during the forward stroke of the tool. During .the return stroke of the tool, the blank arbor is rotated in relation' to. the housing 35 through the distance, preferably of one tooth of the blank 33. This intermittent rotation is accomplished as follows: \Vithin the housing 35 is .rotatably mounted a Worm wheel. 38,

shown in full lines in Figs. 4 and 5 and in dotted lines in Fig. 3, which worm wheel is .driven by means of a worm 39,-operated by a flexible shaft40 (see Figs. 2 and 5) have exchanged their positions.

from the tool operating mechanism in timed relation with the tool, so that the worm wheel 38 will make one-half of a revolution for every full forward and back movement of the tool.

The face of the worm wheel 38 is provided with two rollers 41 and 42, which engage with two grooves 43 and 44, planed at right angles to each other, into the face of a wheel 45. \Vhen the worm wheel 38 is in the position shown in Fig. 4, the roller 41 enters the groove 43 and imparts to the wheel 45 a rotary movement of an accelerating nature. After the worm Wheel has completed one-eighth of a rotation and assumed the position shown in Fig. 5, it will have imparted to wheel 45 one-eighth of a revolution, and the rate of motion or speed of the wheel will have reached its maximum.

s the worm wheel 38 completes another one-eighthrof a revolution, the movement imparted -to the wheel 45 will be of a retarding nature, and the groove 43 of 'the wheel 45 will arrive at the position which the groove 44. assumes in Fig. 4, the roller 41 leaving the groove at this time. During the next quarter turn of the worm wheel 38, the wheel 45 will remain stationary until the first semi-revolution of the worm wheel has been completed and the rollers 41 and 42 The roller 42 will then enter'the groove 44, which I the forward stroke of said tool.

will then be in the position occupied by the roller 41 and the groove 43 of Fig. 4, and the process described above will be repeated. In this way, an intermittent motion is imparted to the wheel 45, which is so timed that a quarter rotation occurs during the return stroke of the cutting tool, while the wheel 45 will remain at rest durin The whee? 45 is secured to an arbor 46, to which is clamped a change-wheel 47. This wheel is geared through an idler 48 to the change wheel 49, .which is clamped to an' arbor 50. This arbor carries a flange 51, provided with are shaped slots 51, shownin Fig. 12. By means of bolts 52 which pass through said slots, the spacing pinion 53 is adjustably secured to the arbor 50. This pinion engages with the master wheel 54,

which is secured to the blank arbor 34.

forward stroke of the tool, an anchor is provided as follows :-To the arbor 55 of the worm wheel 38, is secured a cam 56, Fig. 6, which engages with the 'cam roller 57 of the anchor lever 58, the spring 59 holding the roller in contact with the cam. The lever 58 carries the anchor-toe 60, engaging with the notched anchor-wheel (31, which isclamped to the pinion arbor 50. The cam 56 is so timed that the wheel 61 will be anchored during the forward stroke of the tool and released during the return stroke, these strokes of the tool being-more, fully hereinafter described.

Upon the right hand end of the frame 20,-

drawings it is shown as secured in its center with the ram 71 having a tool operating head 72 at its forward end.

For operating the mechanism at the lefthand end of the frame by the driving pulley 68 at the right hand end, the following flexible mechanism is provided :T he driving pulley 68 carries a ear wheel 73 which engages with a. pinion 4 mounted in an arm 75 extending from the bearing 66. This pinion 74 is coupled to one end of the flexible shaft 40, through which the worm wheel 38 is driven, as hereinabove described. The pulley-arbor 67 also carries a bevel pinion 76, which meshes with abevel wheel 77 mounted in an arm 78 alsoextending from the bearing 66. The wheel 77 is connected through universal joints 79, and an extensible shaft 89 with a bevel gear 81 mounted in an arm 82 at the left hand end of the frame 20.

The gear 81 meshes with a bevel gear 83, which is secured to the end of the shaft :29, which rotates the worm 28 for operating the feeding mechanism for rolling the blank on 'its pitch surface during the cutting operation, as hereinabove described.

It will of course be understood that the .ram 71 slides longitudinally in suitable ways in the support 62, and, if the tool 96 were secured directly to the ram as in said Patent 294,844, the line of motion of the tool would be parallel to a line on the bottom surface of the tooth spaces of the gear being cut, as described in lines 6064' of page 2 of said patent and shown in Fig, 4 thereof. The tool operating head 72 is formedwith a horizontal dove-tail groove 84, and a tool support 85 has a, dove-tail 86 fitting said groove, whereby the tool support may slide transversely of the longitudinal axis of the ram.

An apron 87 is pivoted on the support 85 by a pin 88, and a tool holder 89 is adjustably secured to the front face of the apron. The

securing means for the tool holder comprises on'an arc of a true circle and the gear blank 'is rolled upon its pitch surface during the 95' a block 90 sliding'in a groove in the apron, and a pair of clamping plates 91 and 92 between which the. tool holder 89 is held by bolts 93 and 94. In the'forw'ardly project mg arm 95 of the tool holder 89, is secured a tool or'cutter 96, the arm 95 shown in Figs. 1 and 2 being bent at a slight angle to the longitudinal axis of the ram 71, sothat the tool is secured in said tool holder also at an angle to said axis. This arrangement 1 is shown particularly in Fig. 2.

The tool support 85 is connected with means for sliding it transversely of the longitudinal axisof the ram 71 simultaneously with the reciprocation of said ram. As shown in the drawings, this means consists 4 5 of an arm 97 secured t4) the tool support 85,

as shown in Figs. 1 and 2, and having a pin or roller 98 adapted to'operate in a cam slot 99in .a cam plate 100, which is secured preferably to the support 62 or other part of the any desired shape, but for the purpose'of cutting curved teeth, said slot is curved where "it operates during the cutting part of the tool stroke, and thus produces a varying relative lateral movement between the tool and blank.' The slot maybe straight or parallel with the longitudinal axis'of' the ram 71 during the idle 'part of said stroke. This-curved part of the slot is shown at 101, and the straight part at 102, and in the drawings the curved part is made in the form of an arcof a true circle.

, From the above description it wil'l'be seen that as the ram 71 reciprocates through the medium of the connectingicd and crank and formed by a rack toot machine frame. The cam slot 99 may be of 69, the head 72 is carried with it, and the I tool support 85 j in moving forwardly is guided by the cam slot 99, and caused to slide transversely in the head 72 simultaneously with its forward movement. This 70 combined forward and lateral movement of the tool, in the present form or embodiment of the invention as adapted to the machine of the aforesaid Bilgram Patent No. 294,844, will be in a plane parallel to one which is tangential to the dedendum cone of the gear being cut. On the return stroke of the ram, thetool support'85 is of course caused to reverse its sliding movement in the head 72, and the parts are returned to initial posiso tion. Thus there is illustrated one form of mechanism for giving to the tool a movement in a curved path across the face of the blank, and in this mechanismthe tool support and-all the parts thereon, in- 35 cluding the tool 96, have a translatory moveinent in a curved path, thetool cutting a curved space between the teeth, instead of a straight one, as it would do. without the cam .and slide mechanism. The angular position of the tool takes careof the necessary clearances, When the curved part 101. of the cam slot is made,"as in the drawings,

cutting operation as above described, the I -'t0ol.which is in the well-known form of a rack tooth travels in a similar arc and a gear is cut, as shown, having curved teeth extending in a generally dia onal direction 100 passing in a circular path which is parallel to a plane tangential to the dedendum cone of the gear. Hence the faces of the ear teeth are conjugate to surfaces each 0 which is nerated by the motion of a straight line guided by true circular arcs which lie inplanes parallel to a plane tangential to the dedendum cone of the gear. This is clearly shown in Figs. 13 to 15 in which the gear 33 is shown as meshing with the crown ear 110 having teeth each of the faces ofw ich is a surface generated as abovev described. The tooth 111 is cut away at a and b on planes which are parallel to a plane tangen- 115 tial to the dedendum cone of the gear 33.

The intersection of the surface-a with one and e, The opposite face of the tooth 111 is a surface generated by a line .having a translatory movement and guided by the arcs g and h. i 1 Itis desirable to raise the tool during its return stroke so that the blank may be v is obtained in cutting a curve rotated for a cut on the next tooth, and for this purpose the apron 87 is provided with an offset arm 103, on the end of which is mounted a long roller 104. An arm 105 extending from the support 62 has a lever 106 pivoted at 107, and said lever is provided with a roller 108, which operates in an irregular cam slot 109 in the face of the pulley 68, so that the forward end of the lever 106 depresses the arm 103 as it contacts with the roller 104:. The roller is made sufficiently long to be operated upon by the lever '106 at any time during the transverse reciprocation of the tool support 85. By the action of this lever 106, the tool is alternately raised and lowered, the cam slot 109' being so timed that the tool 'willbe raised during thereturn stroke and will be in its normalcutting positionduring its forward stroke. The tool and apron are shown in cutting position in F ig. 1, and in raised position as they would appear on the return stroke in Fig. 8. The tool is moved through -the blank a suflicient distance before it is 25 raised to insure clearance.

In a pair of bevel gears the teeth of one gear are of course curved in the opposite direction to the teeth of the other. Therefore, by making the cam plate 100 reversible,

so that'it may be used, as shown in Fig. 2, for cutting one of the gears of a pair, and then reversed, as shown in Fig 9, for cutting the other gear of said pair, only one cam is required for cutting two gears. As it is necessary that these gears should be cut extremely accurately, this reversibility of the cam plate is of considerable importance, because in the first place, it means that the gears will be cut to a much better fit than as if two separate cams were used, and that the expense for cam plates will be less.

In Figs. 10 and 11 another form of tool and tool holder is shown. In this instance,

the forwardly projecting arm 95 of the tool holder is straight instead of being at n an gle, and the tool- 96 has its forward end 96 bent at an angle, so that the pro er clearance tooth.

The operation of the machine. may be described as follows: When the pulley 68 is put in motion, a reciprocating movement is transmittedto the ram 71 and the head'72, and al1 of the parts mounted thereon are caused to reciprocate with'the ram. By reason of the cam slot 99 guiding the pin 98, the

tool support 85 is caused to reciprocate transversely of the longitudinal axis of the ram 71, and the too-l 96 therefore travels in a curved path across the, face of the gear blank 33. During the return stroke, the tool is raised to clear the teeth of the blank and for the purpose of allowing plenty of time for the blank to be-rotated to the next tooth, the tool 96 travels some distance away from the blank toward the rear, and during this part of its movement the pin 98 travels in the portion 102 of the cam slot 99. At the beginning of the operation, the blank is so far to one side that the tool will make only a light cut into it. By the spacing mechanism described, the blank is rotated during that after the blank has made one revolution operation, similar to that described, the first operation having correctly generated only one side of each tooth space of the blank.

The readjustment of the tool may be accomplished by re'clamping, while the readjustment of the blank may be effected by loosening the bolts 52, slightly turning the pinion 53 on its arbor 50, and reclam-ping the bolts.

For cutting the mate to the first gear,- if the gear sizes are equal, it is only necessary to substitute another blank, reverse the cam plate 100, and reverse the angle of the tool.- Of course if the mating gears are of unequal diameter, it is then necessary to also change the angle of the blank arbor 34 and theratio of the change-wheels 47 and 49.

ter, and means for rolling the blank relative to the cutter to generate the tooth, of means for giving to the cutter a translatory movement back and forth in a curved path across the face of the blank.

2. In a machine for cutting bevel gears, the combination with means for holding the blank, a cutter, and means for rolling the blank on its pitch cone surface relative to the cutter to generate the tooth, of means for operating the cutterback and forth in a curved p'athacross the face of the blank, thegeneral direction of movement of said cutter being at an angle to an element of the pitch the tool to mounted to reciprocate substantially in' aplane across the face of the blank, a tool operated by said head, means for rolling the 4. In a gear cutting machine, the combination with means-for holding the blank, of a tool operating head mounted to reciprocate substantially in a plane across the face of the blank, a tool support mounted to slide in the head, means for reciprocating the head, and meansfor simultaneously sliding the tool sup-port.

5. In a gear cuttingmachine, the combination with means for holding the blank, of

a tool operating head'mo'unted to recipro cate substantially in a plane across the face neously sliding the tool support, and means of ,the blank, a tool support mounted to slide transversely in the head, means for reciproeating the head, and means for sliding the tool supportv in time "with the reciprocating movement of the head.

6. In a gear cutting machine, the combination with means for holding the blank, of 'a tool operating head mounted to reciprocate toward and from the blank, a tool support mounted to slide in the head, means for re ciprocating the head, and a cam for sliding the tool support transversely as it is moved toward the 'blank by the head. v .7.'In-a gear'cutting machine, the combi nation with means for holding the blank, of a tool operating head mounted to reciprocate toward and from the blank, .a'tool support-mounted to slide in the head, means for reciprocating the head, means for simultafor raising the tool support from the work on its return stroke.

8. In a gear cutting machine, the. combination withmeans for holding the blank, of a tool operatin head mounted to reciprocate toward and from the blank, a tool'support mounted to slide in the head, acam for sliding the tool support and reversible to give two opposed paths of travel to the tool support, and means for reciprocating the head. e

' 9. In a gear cutting machine, the combination with means for holding the blank, of

' a tool operating head mounted to recipro cate toward and from the blank, a tool support mounted to slide in the head, a tool holder mounted to support the tool at an angle to the path of movement of the head,

means for reciprocating the head, and means for simultaneously slidingthe tool support.

10. In a gear cutting machine, the combination with means for holding the blank, of a tool operating headmounted to reciprocate toward and from the blank, a tool support mounted to slide in the head, a tool holder secured to said support, a tool in said holder having its cutting 'face inclined relative to the path of movement of said head,

means for reciprocating the'headg'and means for simultaneously slid ng the tool support.

11. In a gear cutting machine; the combi-- nation with the frame, an arbor-for supporting the gear blank in operative position, means forrolling said blank on its pitch surface during the cutting operation, means fonintermittently rotating the blank on its arbor, a tool operating, head mounted to reciprocate substantially in a plane across the. face of the blank, a tool operatedby said head, and means for reciprocating-thehead in time with the blank rotatingmeans, of

means for causing with each reciprocation of said head a relative movement between said tool and said blank holding means transversely of the path of reciprocation of said head.

12. In a gear cutting machine, the combi,

nation with the frame, and means on the rolling said blank on" its pitch surface du'rmg the cutting operation, of a tool operat-' ing headmounted to reciprocate in a plane,

across the face of the blank, a tool support frame for supporting a gear blank and for mounted to slide in the head, a tool secured,

head, and means for simultaneouslysllding the tool'support. 13. In a gear cutting machine, the combination with the frame, and means on the to said support, means for reciprocatin the frame for supporting a gear blank and for rolling said blank on its pitch surface during the cuttingomration, of a tool operat-. ing head mounted to reciprocate in a plane across the face of the blank, a tool support mounted to slide in the head, a tool secured to said support, means for reciprocating the head so that the tool traverses the faceof the blank as the latter is rolled on its pitch surface, and means for sliding the tool support in timewith the reciprocating move ment of the head. 14. In a gearcutting machine, the combination with the frame, an arbor for sup-' porting the gear blank in operative position,

means for rolling said blank on its pitch surface during the cutting operation, and

means for intermittently rotating the blank on its arbor, of 'a tool operating head mounted to reciprocate substantially in a plane across the face of the blank, a-tool support mounted to slide in the head, a tool secured to said support, means for reciprocating the head in time with the blank rotating means,

and means for simultaneously sliding thof tool support.

15. In a'gear cutting machine,the' combination with the frame, an arbor for supporting the gear blank 1n operative position, means for rolling said blank on its pitch surface during the cutting operation, and means for intermittently rotating the blank on its arbor, of a tool operating head mounted to reciprocate Substantially in a plane across theface of the blank, atool support mounted to slide in the head, a tool secured to'said support, means for reciprocating the head in time with the blank rotating means, means for simultaneously sllding the tool support, and means for raising the tool from the work on its idle stroke, whereby the tool is moved transversely on its cutting and return strokes, is raised from the work on its return stroke, and the blank is rotated as the tool reciprocates in raised position on its return stroke.

16. Ina gear cutting machine, the combination with means for holding the blank, of a tool operating head mounted to reciprocate toward and from the blank, a tool support mounted to slide in the head, means for reciprocating the head, and means for sliding the tool support transversely through a part only of its travel with said head.

17. In a gear cutting machine, the combination of means for supporting the blank,

to generate the tooth, of means for operat-' ing the cutter in a curved path across the face of the blank, and means for positively holding the blank against all rotatlon on its axis, except that due to the said rolling means, during the cutting operation.

19. In a machine for cutting bevel gears, the combination with means for supporting the blank, a cutter, and means for rolling the blank on its pitch cone surface relative to the cutter to generate the tooth, of means for operating the cutter including guiding means for moving the cutter 'in a curved path across the face of the blank.

20. In a gear cutting machine, the combiation' with means for supporting the blank, a

cutter, and means for rolling the blank rela-' tive to the cutter to generate the tooth, of

, means for operating the cutter in a curved path on the arc of a circle across the face of the blank.

21. In a gear cutting machine, the combination of a device for supporting the blank,

a cutter device, means for guiding the cutter device in a curved path across the face of the blank to cut a curved tooth, and means for moving one only of said devices to gena cutter device, means for producing. a rela-- tive movement between said devices causing the cutter device to travel in .a curved path 'acrossthe face .of the blank to cut a curved tooth, and means for moving one only of said devices .to generatethe tooth.

23. In a gear cutting machine, the combination of a blank support, a cutter, means for movin thecutter in a curved. path across the face of the blank tangentially of the dedendum surface, and means for producing an additional relative movement between said blank and cutter to generate the tooth.-

24. A method of cutting gears consisting in movinga tool in a curved the tooth, and rolling the blan c on its pitch surface to generate the tooth.

25. A'method of cutting bevel gears consisting in moving a tool in a curved path to shape the tooth, and producing a relative rolling motion between the blank and! the tool on the pitch cone surface of the blank to generate the tooth! 26. A method of cutting ears consisting in moving a tool in a curved path and tangentially of the blank to shape the tooth, and producing a relative motion between the blank and the tool to generate the tooth.

27. In a gear cutting machine, the combination with means for holding the blank, of 'a head-mounted to reciprocate substantially in a plane across the face of the blank,

r crate the tooth.

28. The method of cutting bevel gears which consists in movin a tool across the face of the blank While snnultaneously producing a relative lateral movement of the tool and blank during the cutting movement to effect a curved 'cut and producing a; relative intermittent lateral movement between the tool and blank to cut on successive teeth and a relative motion between the tool and blank to generate the tooth;

29,. In a gear cutting machine, the com bination with means for supporting the blank, of a cutter, means for moving the cutter across the face of the blank, means for producing a relative lateral movement ath to shape between the cutter and blank during the cutting. movement to effect a'curved cut,

means for producing a relative intermittent lateral movement between the cutter and blank to cut on successive teeth, and means for producing an additional relative movement between the cutter and blank to gen- 1 crate-the teeth.

=' the blank and cutter along the plane of the curved pathofmovement of the cutter.

'31. The method of forming the side face of a curved gear tooth, consisting in causmg a cutter to describe an ancuatepath around an axis and across the faceof the blank, and simultaneously producing relative rolling motion between the blank and cutter along a. plane tangent to the pitch line of. the blank and normal to the'cutter axis.

32. In a machine for cutting curved teeth on bevel gears, the combination with'a blank carrier, of a cutter having a cutting portion which is movable through the blank in a curvilinear path-lengthwise of the tooth to be formed,-the axis of the cutter bein disposed at'an'angle to the axis of the blank carrier, adjusting means for changing the position of the blank carrier relatively to the cutter, means for imparting'a relative rolling motion to the cutter and blank carrier,.and means 'for advancing the cutter through the blank during said relative rollingnrotion.

83. In a gear cutting machine, the combination with means for .suppo ng the blank, of a cutter, means for moving the cutter forward and back across the face of the during the cutting movement to eflect' a curved cut, means for producin a relative intermittent lateral movement tween the cutter and blank to cut on successive teeth,

means for producing an additional relative movement between the cutter and blank togenerate the tooth, and means for raising the cutter from the work on its back stroke.

34. In a gear cutting machine, the combination of a,device for supporting the '55 blank, a cutter device, means for guiding the cutter device in a path curved in two directions across the face of the blank to'cut a curved tooth, and. means for moving one of said devices to generate the tooth.

35. In a gear-cutting machine, the combination of a device for supporting the blank, a cutter device, means for producing a relative movement between said devices causing the cutter device to travel in a path curved back and forth across the face of the blank to cut a curved tooth, and means for moving one of said devices to generate the tooth.

36. In a gear cutting machine, the combifor moving the cutter in a curved path across the face of the blank and parallelto a plane tangential to the pitch surface thereof, and means for producing an additional relative movement between said blank and cutter to generate the tooth.

' 38. A method of cutting gears consistin in moving a tool in a path portions of whic are curved in o' posite directions circumferentially of the lank to shape the tooth, and

rolling theblank on its pitch surface togn- 4 erate the tooth. I

39. A method of cutting bevel gears consisting in moving a tool in a curved path to shape the tooth, and producing-a relative rolling motion between the blank and the tool to generate the tooth.

40. A method of cutting gears consistin in moving a tool in a curved path paralleI -to a planetangential to the pitch surface of the blank to shape the tooth, and producing a relative motion between-the blank and the tool to generate the tooth.

41. In a machinefor cutting curved gear teeth, the combination with a blank carrier,

of a cutter having a cuttin portion which is movable through the blan in a curvilinear I path lengthwise of thetooth to be formed,

- the axis of the cutter'being disposed at an nk carrier, adjusting means for changin the position of the blank carrier relative y to the cutter, means for imparting a relatiyerolling motion to the cutter and blank carrier, and meansfor advancing the cutter through the blank during said relative rolling motion.

42. In a gear cutting. machine, the combination of means for supporting a blank, a cutter, means for operating the cutter across the face of the blank in a curved path'and shifting the relation of the cutter .and blank during the cutting movement in a manner to maintain uniform clearance, and means for simultaneously producing relative rollangle to the axis of the b ing motion between the blank and cutter along a plane-tangentto the pitch line of the blank.

- across the face of the blank in a pathcurved back and forth in opposite directions circumt'erentially of the blank and shifting the relation of the cutter and blank during the cutting movement to maintain uniform clearance, and means for simultaneously producing relative rolling motion between the blank and cutter along a plane tangent to -'the.pitch line of the blank.

44. The method of cutting curved tooth gears, consistin in moving a tool in a curved path to s ape the tooth and shifting a the relation of the cutter and blank during the cutting movemenls to maintain uniform clearance, and producing relative rolling motion between the blank and cutter along a plane tangent to the pitch line of the blank to generate the tooth.

45. The methodof cutting curved tooth gears, consisting in moving a tool in a path .cfurvedback and forth in opposite directions circumferentially of the blank to shape the tooth and shifting the relation of the cutter and blank during the cutting movement to maintain uniform clearance, and simultaneously producing relative rolling motion between the blank and cutter along a plane tangent to the pitch line of generate the tooth.

46. A gear cutting machine, comprising a cutter, means for moving said cutter in a curved path in a plane, and means for prothe blank to ducing relative rollin motion between said,

a cutter, means for moving said cutter in a curved path in a plane, means for rollin a blank along said plane, and means for re 'atively rotating said blank and cutter step by step around the blank axis.

In testimony whereof I aflix my signature in presence of two witnesses. 1

CHARLES E. DERR. Witnesses:

MILO L. BAILEY, 7 E. GROAT. 

